Avaliação de uma nova carga na composição de revestimentos externos aplicados em isoladores de alta tensão.

Abstract

In this research the performance of polymeric coatings applied to suspension glass insulator was evaluated. The coatings were composed of Silicone Rubber at Room Temperature Vulcanized added to alumina trihydrate and a new filler at different mass proportions. The new filler was electrically characterized by measuring of this dielectric constant and loss tangent. Insulators samples coated with various compositions were subjected to cyclic salt fog tests whose purpose was to degrade the insulation. The performance of the coatings was evaluated from leakage current measurements, harmonic analysis and monitoring recovery of hydrophobicity. The dielectric constant of the new filler was approximately 3,0 over wide frequency range and loss tangent around 10-3. The evaluation of leakage current peak values showed that the addition of low concentrations of new filler to Silicone Rubber provided good performance isolation. Analysis of Total Harmonic Distortion and the ratio between 3rd and 5th harmonics showed the aging of samples during the test. Monitoring of hydrophobicity, after execution the cyclic salt fog test indicated that the coatings showed partial or total recovery of hydrophobicity. In general, the best results were obtained for the coatings that contained 5 wt% of the new filler.